I am planning to add Grundfos MQ3-35 96860172 3/4 HP Pressure Booster Pump - 115 Volt with a Pressure Reducing Valve in front to my townhouse but I am unsure where to install it. I have a water treatment system (carbon tank, water softener, with a flow on demand system) install just after the water meter. I want my water treatment company to install it when they switch out the carbon tank in November, but they say they won't do it unless I buy the pump from them and right now they won't even give me a quote (I assume their price for the pump it heavily marked up). Also they say that Grundfos is coming out with a better one in the fall (I think it is the CMBE
Model but they won't say). So if I do it myself, the pipes are plastic around the water treatment system so it not hard to do yourself, would the booster pump go before the water system or after it? I would think before but I am not sure. I still hope to have a plumber do it so its right, but I want to know if hiring one doesn't work out.

Also, why this push back on the pump? I am paying the plumber for the labor after all, the work shouldn't take more than an hour tops, and they have to come anyway to do the carbon tank. Something is better than nothing right?

I would think before the filter, but I 'd call Grundfos and ask them.

U.S.A.Grundfos Pumps Corporation17100 W. 118th TerraceOlathe, Kansas 66061Telephone: (913) 227-3400Fax: (913) 227-3500

I am assuming you are wanting to raise your system pressure?

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I still hope to have a pumper do it

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Do you mean "plumber"?

>I would think before the filter, but I 'd call Grundfos and ask them.

I will if I have to, but I am not sure their support people will be able to answer. They are not plumbers and I can barely get them to comment on the products they sell. I really can't see them being able or wanting to talk about it which is why I was hoping to get advice from someone that really knows what to do in this case.

>Do you mean "plumber"?

Yes, I didn't proof read well enough, I fixed it in the original question.

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Originally Posted by jkerich

>I would think before the filter, but I 'd call Grundfos and ask them.

I will if I have to, but I am not sure their support people will be able to answer. They are not plumbers and I can barely get them to comment on the products they sell. I really can't see them being able or wanting to talk about it which is why I was hoping to get advice from someone that really knows what to do in this case.

>Do you mean "plumber"?

Yes, I didn't proof read well enough, I fixed it in the original question.

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I called Grundfos support and they said it should probably go after the water treatment stuff. There should be no basin of water after the pump and while he didn't think the carbon or sand cylinders counted, better to be safe. They also said that the reported leaks on the model I am looking at is because the pump should not have more than 40 PSI coming in and people are installing the Pressure Reducing Valve after pump instead of before the pump intake as it says in the install instructions so there was too much pressure coming in causing it to leak. So after it is then.

The consumer reviews on the pump seem to be pretty good. For the price, it should do a great job for you. You might want to consider putting a small pressure tank after the pump if you start having problems with the pump cutting on/off frequently.

The model does come with small pressure tank inside the unit so you don't need an external tank.

I still wonder if the Grundfos support answer is correct. He didn't really sound like he was sure, just playing it safe.

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There should be no basin of water after the pump

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Not too sure I understand that part. Basin of water??

Yes, the booster pump has a TINY pressure tank attached to it, but if you start having problems with the booster pump cycling frequently, a five or ten gallon tank would be helpful.

One thing about it. If you put the pump after the filter and decide you don't like it, then I wouldn't think it would be a big deal to just move it before the filter.

Please let us know how it works out. You have asked a question that we don't see very much here. Be interesting to see the outcome.

I will post what happens. I think the "basin of water" is some sort of tank that could be over pressurized because the extra pressure from the pump. Like I said, I don't really think their support people know what they are talking about. They sure aren't plumbers.

I am switching the carbon tank out in November so the Water people have to give me a quote to do the work at the end of October and also tell me what this "better" pump is they want use instead. So either I or they will be doing it in November, I already installed the 20 amp output so I am ready to go. I will let you know what happens, etc. then.

Again, if someone really knows, please post.

The Grundfos CMBE 1-44 (120v) booster pump was installed yesterday and it was in front of the water treatment system by the company that originally installed the water treatment system. I took 2 pictures; one is the booster pump and the other the water treatment system. The pictures show how the plumbing was changed and where the pump was added in. The pump is set to 75 PSI so I have ~61 PSI on the second floor and I can really see the difference when I use the water. The pump does not require a PRV since the pump intake is supposed to handle the pressure (40/42 PSI). So far the pipes have not exploded because the increase in pressure.

Attachment 47982

Attachment 47983

Thanks for letting us know your result. I don't think you will have any exploding pipes, but I'd put in a PRV (cheap) after the booster pump in case the pump malfunctions and does not cut off. Unlikely, but could happen.

When you're using water, how often does the pump cycle? Just curious.

>When you're using water, how often does the pump cycle? Just curious.

The pump comes on after a second or so after the water begins to flow in the pipe. So basically it's running whenever water is being used to keep it at the 75 PSI. When the water is not being used I have not seen it come on, which I guess is why it's energy efficient.

>but I'd put in a PRV (cheap) after the booster pump in case the pump malfunctions and does not cut off

I assume "PRV" stands for Pressure Reducing value which is already built into the pump. What should go after the pump, according to the inspector, is a valve to cut off the water incase the pipe explodes (or more likely is leaking). I am not sure what it looks like or what the name is for the part but I don't think PRV is the type of value that does that.

The WSSC inspector for the county finally came and said that because the pipe was plastic a "blow out valve" would have to be installed after the pump to cut of the water if the pipe breaks. The work is to be done tomorrow so I will take new pictures of the final setup.

P.S. Why does the inspector put his sticker on the breaker box vs. the wall where the pump is or on the pump its self?

I have attached new pictures of the pump after they added a pressure relief valve just after the booster pump. The pressure relief valve (PRV) was set to 100 PSI and is suppose to open automatically if the pressure is too high to stop the pipe from exploding. I told that the inspector would have required it if the pipe where copper as well.

The valve is suppose to close if the pressure goes under 100 PSI again. The water is being sent into the sub-pump hole via a white hose that is running down the black sub-pump pipe from the PRV.